The superheated steam technology is expected to have wide applicability, and therefore, intensive studies have been made concerning dehydration, fresh food processing and so on. In many cases, however, it could not be put into practical use for certain reasons, e.g., too much energy is required to generate high-temperature superheated steam; energy that dissipates as heat increases with temperature; the production cost greatly increases.
Under such circumstances, efforts have been made to improve the efficiency and effectiveness so as to reduce the cost, improve the performance and expand the range of applications. As a result, the practical use of the superheated steam technology is now discussed in wide applications, e.g., non-oil processed foods, evaporation of solvent for casting films, production of bamboo charcoal for hydroponics, dehydration of wood flour and prevention of mold growth therein.
The generation of low-temperature, active superheated steam is realized by an electromagnetic induction type superheated steam device, in which superheated steam can be generated with an induction heating unit placed in a high-frequency magnetic field and by supplying heat from eddy-current losses or hysteresis losses inside the induction heating unit (for example, see Patent Literature 1).
As it is thought that hydroxyl radicals contribute greatly to the reactivity of superheated steam at a relatively low temperature (about 300° C. or less), treating the generated superheated steam by discharge has been proposed so as to efficiently generate hydroxyl radicals in the superheated steam (for example, see Patent Literature 2).